Topic: CB550 throttle resistance question

[tg305]

The throttle pull on my 78 CB550K is a bear, compared with any of my other bikes.  Is this common with the older model Hondas  or is there a way to reduce the resistance/spring load of the carb return spring setup?  I have two sets of carbs and they are both tough to twist open....    cables move freely when loose and have been lubed.     thanks  Tim

[TwoTired]

Some CB550s have stiffer throttle action than others due to return spring differences.  Of course, internally frayed, worn cables can also cause stiffness.  I recall a couple times where the throttle got progerssively stiff until it eventually snapped.  These worked freely while off the bike, misleading correct diagnosis of the problem.  Other causes of stiff throttles have been cable routing problems.  Sharp bends, and kinks really increase the friction when under any kind of tension at all.  I've cured a couple stiff throttled bikes just by rerouting the cable so they have the least amount bends and the bend radiuses were as close to straight as possible.  Also, when different style or length of handlebar is used, shorter or longer cables are needed to minimized cable route bends and bend radius.

Another possible cause of stiff throttle is when the slides don't move freely in their bores.  Usually after the bikes has been sitting for some time.  Dried fuel deposits can impede the free movement and make the throttle quite stiff. Then, of course, you need a heavy return spring to get them closed again with your hand off the throttle.  Cleaning the slides, or simply operating the bike regulary for some period of time can free these up.  Depends on your patience, and tinkering inclinations.

Cheers,

[phylo101]

Do two things - remove the closing cable and throw it away. If its gummed up youre not only pulling the throttle cable against the return spring but trying to push the cable inner of the second cable thru a gungy inner. Its totally superfluous. The, remove the opening cable and saok thoroughly in something mineral-based, like british Three-In-One oil. After a while this breaks down the teflon inner coating thats put in modern cables to assist friction-free cable movement....but when this breaks down it unbonds from the cable outer and you can draw it out and junk it.This way you add a couple of thou clearance between the cable inner and outer, leaving more "gallery" room for lube and less chance of gumming up due to gunge and narrow clearances. Works a treat.

phylo